package com.company.sendemo.basics.amJavaCollection.javamap;

import java.util.Arrays;
import java.util.HashMap;

public class Map {
    public static void main(String[] args) {
        //HashMap 可看下面类
        //TODO com.company.sendemo.basics.zzInterview.select.Twelve

        //Map    键不可重复 值可重复
        //          HashMap(key value 都允许为null)
        //          HashTable(key value 都不允许为null)
        //          TreeMap
        HashMap map = new HashMap();
        map.put("name",null);
        map.put("name","jack");
        System.out.println(map.size());//1


    }
}
